The goal of the Environmental health Sciences Center (EHSC) at the Mount Sinai school of Medicine is to conduct research which identifies, ameliorates and ultimately prevents human diseases caused by toxic environmental agents. Our principal research strategy is to delineate quantitative dose-response relationships between environmental exposures and human illness. Environmental health research in the mount Sinai EHSC is inherently multidisciplinary. Epidemiology is the unifying discipline. It provides sophisticated techniques for linking human disease with environmental exposures. Epidemiology relies heavily on clinical medicine. Clinical evaluations to define the impact of environmental exposures on human health are included in many of our studies; they are made possible by the unique location of the Mount Sinai EHSC in a major medical center. Detection of subclinical physiologic and biochemical changes, resulting from low-level exposures to environmental toxins, mandates collaboration of epidemiologists with toxicologists, pathologists and cell biologists. Through this collaboration, "biological markers" of exposure and effect are validated and then incorporated into our epidemiologic studies. Disease entities of greatest interest in the Mount Sinai EHSC are cancer, pulmonary disease, neurotoxic illness and heavy metal intoxication. The research program in asbestos-related disease if of international reknown. Following the change in leadership of the mount Sinai EHSC in 1985, transition has occurred in the research strategy. The major consequence of this change is a trebling of research capacity in quantitative epidemiology. The level of biostatistical involvement also has increased. Utilization of "biological markers" has become more frequent and will increase further. This transition builds on the strong foundation of expertise in environmental science in the mount Sinai EHSC. Its consolidation requires continuing support for development of an epidemiology laboratory, for additional increments in biostatistical capability and for enhancement of our ability to assess exposures. The Mount Sinai EHSC is unique in its focus on human health. The rationale for its existence is the need to develop quantitative understanding of the diseases caused in man by environmental toxins.